Solid-phase extraction (SPE) is a separation method where various dissolved or suspended compounds in a mixture are separated from other compounds in the mixture by bringing them into contact with a chemically defined solid phase material. The separation is based on the physical and chemical properties of the compounds and their ability to interact more or less strongly with the solid phase material. Analytical laboratories use solid phase extraction to concentrate and purify samples of specific compounds, or analytes, for analysis. Solid phase extraction can be used to isolate analytes of interest from a wide variety of matrices, including urine, blood, water, beverages, food, soil, and animal tissue.
In order to separate a mixture into desired and undesired components, SPE exploits the differences in affinity of individual solutes in a mixture that are dissolved or suspended in a liquid for a solid material, typically porous, through which the sample is passed (known as the solid phase). The result is that typically the desired analytes of interest and/or undesired impurities in the sample are retained on the solid phase during a loading stage. Subsequent exposure of the solid phase material to solvents or solvent mixtures of increasing elution ‘strengths’ leads to elution of the weakly bound material, typically impurities, followed by the analyte(s) of interest. The portion that passes through the solid phase is collected or discarded, depending on whether it contains the desired analyte(s) or undesired impurities.
When a polar compound in an aqueous medium is to be extracted a stationary phase containing non-polar functionalities may be employed, which may consist of short carbon chains bonded to an inorganic material such as silica or other hydrophobic entities chemically included in a polymer using appropriate monomers or compounds. This type of stationary phase will adsorb polar molecules which can then be eluted and collected as the eluting solvent polarity is progressively decreased.
Mycotoxins are toxic secondary metabolites produced by one or more species of spore-bearing fungi that colonize food crops in the field or food commodities post-harvest. Some species of fungi produce more than one mycotoxin and food products may be contaminated by more than one species. In addition to their toxicity, many mycotoxins have also been implicated as carcinogens and genotoxins. Mycotoxins exhibit a diverse range of chemical structures and associated physicochemical properties, creating significant challenges for their extraction and subsequent detection and quantitation. Regulation and legislation for testing of mycotoxin contamination has established which mycotoxins are globally significant for a variety of food products. EU regulations gives extensive details of the food contamination issues with mycotoxins and recommended limits of contamination, see 2006R1881:20100701.
Current methods for extraction of mycotoxins may employ specific anti-toxin antibodies, often used in immunoaffinity columns, or SPE with a hydrophilic lipophilic balanced (HLB) copolymers. The disadvantage of these methods is that extraction using antibodies is costly and sensitive to storage conditions, while HLB copolymers are inefficient due to problems with retaining the adsorbed mycotoxins during the washing procedures, especially when strong eluting solvents are used, resulting in unacceptably low recoveries.
WO03101580 discloses a method of binding mycotoxins to a solid carrier by contacting a mycotoxin containing solution, suspension or aerosol with a mycotoxin imprinted polymer and then separating the bound mycotoxin from the solution, suspension or aerosol.
EP2189213 discloses an adsorbent for removing toxicants from blood or plasma. The adsorbent comprises a divinyl benzene based porous bead where monomers or polymers are covalently linked to pendant vinyl groups of the porous bead leaving the monomers or polymers protruding from the bead surface. Suitable monomers may be primary, secondary or tertiary amines, for example 4-vinylimidazole and 2-vinylpyridine. According to the inventors of EP2189213, these monomers or polymers render the adsorbent more hemocompatible by minimizing the adsorption of proteins and cells on the surface of the adsorbents.
US20060058413 discloses a porous adsorbent material for removing albumin-bound toxins, drugs or pharmaceuticals. The adsorbent comprises 5-30 wt % of vinylimidazole monomers and 50 to 85 wt % of divinyl benzene.